We propose to quantitatively investigate the transparency of normal and pathological corneas in both rabbits and humans, using two methods which will provide the basis for developing two new clinical instruments. The first of these methods is measurement of the angular dependence of light scattered from the cornea, for which a modified slit-lamp biomicroscope will be used. This method provides information on the size of the scattering centers in the cornea and their number. The second method is that of inelastic light scattering, for which the light source is a low power HeNe laser. Inelastic light scattering allows study of the motion of the scattering centers, in this case primarily the stromal fibrils and keratocytes. The methods will be used clinically to help identify particular pathologies in the human cornea, and to quantitatively follow the development of the pathologies in time. Pathologies of known character will be artificially induced in the rabbit corneas for study by the light scattering methods. When the methods are then applied to pathological human corneas these pathologies can be identified.